Question 727 of 1,031

Describe Azure architecture and services →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is to distribute VMs across different power and cooling racks. This is correct because fault domains in Azure Availability Sets represent groupings of hardware that share a common power source and network switch; by placing VMs into multiple fault domains, you isolate them from a single point of physical failure, such as a rack-level power outage or cooling system malfunction. On the Microsoft Azure Fundamentals AZ-900 exam, this concept tests your understanding of high availability within a single datacenter, often appearing alongside questions about update domains—a common trap is confusing fault domains (physical hardware separation) with update domains (logical reboot sequencing). A reliable memory tip is to think of “fault” as “floor” or “rack failure,” while “update” is about “planned maintenance.”

AZ-900 Describe Azure architecture and services Practice Question

This AZ-900 practice question tests your understanding of describe azure architecture and services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A company is deploying a critical application on Azure Virtual Machines. They need to ensure that the application remains available during Azure platform updates. They also want to distribute the VMs across fault domains within an availability set. What is the primary purpose of fault domains?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.

Question 1hardmultiple choice

Full question →

A
To distribute VMs across different power and cooling racks
Fault domains group VMs that share the same power and network infrastructure. By placing VMs in multiple fault domains, you ensure that a single rack failure does not affect all VM instances.
B
To distribute VMs across different Azure regions
Why wrong: Fault domains exist within a single region and datacenter. Cross-region distribution is handled by availability zones or paired regions.
C
To distribute VMs across different availability zones
Why wrong: Availability zones are physically separate datacenters within a region. Fault domains are a finer-grained separation within a single datacenter.
D
To distribute VMs across different virtual networks
Why wrong: Virtual networks are logical network isolation and are not related to physical failure domains.

Full breakdown with real-world context →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

To distribute VMs across different power and cooling racks

Fault domains represent groupings of hardware that share a common power source and network switch. By distributing VMs across multiple fault domains within an availability set, Azure ensures that if a power or cooling failure occurs in one rack, only the VMs in that fault domain are affected, keeping the application available on VMs in other fault domains.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✓
To distribute VMs across different power and cooling racks
Why this is correct
Fault domains group VMs that share the same power and network infrastructure. By placing VMs in multiple fault domains, you ensure that a single rack failure does not affect all VM instances.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
To distribute VMs across different Azure regions
Why it's wrong here
Fault domains exist within a single region and datacenter. Cross-region distribution is handled by availability zones or paired regions.
✗
To distribute VMs across different availability zones
Why it's wrong here
Availability zones are physically separate datacenters within a region. Fault domains are a finer-grained separation within a single datacenter.
✗
To distribute VMs across different virtual networks
Why it's wrong here
Virtual networks are logical network isolation and are not related to physical failure domains.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates confuse fault domains with availability zones, but fault domains are a rack-level isolation mechanism within a single datacenter, while availability zones span multiple datacenters within a region.

Detailed technical explanation

How to think about this question

An availability set logically groups VMs into up to 3 fault domains, each backed by a separate rack with its own power and network. Azure guarantees that VMs in different fault domains are not updated simultaneously during planned maintenance, and a hardware failure in one fault domain does not cascade to others. This is critical for applications that require an SLA of 99.95% when using two or more VMs in an availability set.

KKey Concepts to Remember

Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.

TExam Day Tips

Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this AZ-900 question test?

Describe Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: To distribute VMs across different power and cooling racks — Fault domains represent groupings of hardware that share a common power source and network switch. By distributing VMs across multiple fault domains within an availability set, Azure ensures that if a power or cooling failure occurs in one rack, only the VMs in that fault domain are affected, keeping the application available on VMs in other fault domains.

What should I do if I get this AZ-900 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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